Roles of silver co-catalyst on gallium oxide for photocatalytic CO2reduction to CO

Abstract

It is well known that Ag loaded Gallium oxide (Ag/Ga2O3) promotes photocatalytic CO2reduction to CO. However, the role of the Ag co-catalyst in the CO2reduction has not been clarified. We have intended to find the relationship between the state of Ag loaded on Ga2O3and their activity for the photocatalytic CO2reduction. To achieve this, we have tried to control and stabilize the loading state of Ag on Ga2O3during their use for the photo-catalytic CO2reduction by adding methanol as a reducing agent. It is confirmed that methanol stabilizes the particle sizes of Ag nanoparticles (Ag-NPs) loaded on Ga2O3under the photocatalytic CO2reduction condition and is hardly decomposed to produce CO. Using Ga2O3loaded with size-controlled Ag-NPs as a photocatalyst for the CO2reduction, it is found that Ag-NPs with their sizes within 10-30 nm are active sites for the photocatalytic CO2reduction and the catalytic activity linearly increases with the increase of the number density of Ag-NPs. However, a higher Ag loading amount over 1.0 wt% promotes aggregation of Ag to be larger metal particles over 70 nm which are not active for the CO2reduction. (Figure Presented).